Method and apparatus for redundant signaling links

Abstract

According to at least one embodiment of the invention, a protocol for managing redundant signaling links to form a reliable signaling connection is provided. The protocol has an initialization phase, in which the availability of signaling links is determined and an available signaling link is selected and activated, followed by an operational phase in which the activated link is used for sending signaling messages for a higher-level protocol. During the operational phase both links are monitored for availability using a query and reply technique. Should either link fail, a status message is sent to the remaining available link along with an activity switchover being performed, as required, depending on whether the failed link was the active link. The higher-level protocol process running on the media gateway performs management of the links, and the media gateway controller operates as a slave, whereby it need not initiate nor control any of the activities for management of the signaling links, thereby reducing the processing burden placed upon it. However, optionally, a media gateway controller may request a link switchover, which may be used to support link maintenance activities or link congestion avoidance measures.

What is claimed is: 
     
       1. A method comprising the steps of:
 initializing a plurality of links between a media gateway and a media gateway controller; 
 activating a first link of the plurality of links; 
 registering the first link for communication of call control signaling information by a higher level process running on the media gateway, wherein the higher level process performs management of the links, while the media gateway controller operates as a slave to the media gateway; 
 monitoring the first link by transmitting an internet control message protocol (ICMP) echo request over the first link and over a second link; 
 waiting for an ICMP reply message within a predetermined period of time on each of the first and second links; and 
 when no reply message is received on the first link, transmitting a status message on the second link to indicate a fault on the first link. 
 
     
     
       2. The method of  claim 1  wherein the step of initializing further comprises the step of:
 determining whether each of the plurality of links is available for use. 
 
     
     
       3. The method of  claim 1  wherein the higher level process is an H.248 process. 
     
     
       4. The method of  claim 1  wherein the step of activating the first link of the plurality of links further comprises the steps of:
 transmitting a link activation message for the first link; and 
 receiving a link activation acknowledgement message for the first link. 
 
     
     
       5. The method of  claim 4  wherein the step of registering the first link for communication of call control signaling information by a higher level process further comprises the steps of:
 transmitting a service change message; and 
 receiving a service change reply message. 
 
     
     
       6. The method of  claim 5  wherein the service change message and the service change reply message are H.248 messages transported as user datagram protocol (UDP) packets over internet protocol (IP) over asynchronous transfer mode (ATM) links. 
     
     
       7. The method of  claim 4  wherein the step of transmitting the link activation message for the first link involves the media gateway transmitting the link activation message to the media gateway controller. 
     
     
       8. The method of  claim 7  wherein, for the communication of the call control signaling information, the media gateway controller exerts control over the media gateway. 
     
     
       9. The method of  claim 8  wherein the call control signaling information conforms to Recommendation H.248. 
     
     
       10. The method of  claim 8  wherein, for the communication of the call control signaling information, the media gateway controller further exerts control over a second media gateway coupled to the media gateway controller by a second plurality of links. 
     
     
       11. The method of  claim 1  further comprising the step of:
 selecting the first link for use. 
 
     
     
       12. The method of  claim 11  wherein the first link is selected based upon a response time on the first link relative to response times on other links of the plurality of links. 
     
     
       13. The method of  claim 12  wherein the first link is selected based on having an earliest response among the plurality of links. 
     
     
       14. The method of  claim 1  wherein registering the first link for communication of call control signaling information by a higher level process further comprises:
 registering the first link such that the higher level process considers the plurality of links to be a single signaling connection. 
 
     
     
       15. The method of  claim 1  further comprising:
 a more populous plurality of media gateways; and 
 a less populous plurality of media gateway controllers, wherein, for link management, the more populous plurality of media gateways exert control over the less populous plurality of media gateway controllers according to a lower-level process, and, for bearer traffic management, the less populous plurality of media gateway controllers exert control over the more populous plurality of media gateways according to the higher-level process. 
 
     
     
       16. A method comprising the steps of:
 monitoring a plurality of links between a media gateway and a media gateway controller; 
 monitoring a first link of the plurality of the links by transmitting an internet control message protocol (ICMP) echo request over the first link and over a second link; 
 waiting for an ICMP reply message within a predetermined period of time on each of the first and second links; 
 determining a failure affecting the first link; 
 when no reply message is received on the first link, transmitting a status message on the second link to indicate a fault on the first link; 
 activating the second link of the plurality of the links; and 
 registering the second link for communication of call control signaling information by a higher level process. 
 
     
     
       17. The method of  claim 16  further comprising the step of: updating routing tables to allow utilization of the second link. 
     
     
       18. The method of  claim 16  wherein the higher level process is an H.248 process. 
     
     
       19. The method of  claim 16  wherein the step of activating the second link of the plurality of links further comprises the steps of:
 transmitting a link activation message for the second link; and 
 receiving a link activation acknowledgement message for the second link. 
 
     
     
       20. The method of  claim 19  wherein the step of registering the second link for communication of call control signaling information by a higher level process further comprises the steps of:
 transmitting a service change message; and 
 receiving a service change reply message. 
 
     
     
       21. The method of  claim 20  wherein the service change message and the service change reply message are H.248 messages transported as user datagram protocol (UDP) packets over internet protocol (IP) over asynchronous transfer mode (ATM) links. 
     
     
       22. The method of  claim 19  wherein the step of transmitting a link activation message for the second link involves the media gateway transmitting the link activation message to the media gateway controller. 
     
     
       23. The method of  claim 22  wherein, for the communication of the call control signaling information, the media gateway controller exerts control over the media gateway. 
     
     
       24. The method of  claim 23  wherein the call control signaling information conforms to Recommendation H.248. 
     
     
       25. The method of  claim 23  wherein, for the communication of the call control signaling information, the media gateway controller further exerts control over a second media gateway coupled to the media gateway controller by a second plurality of links. 
     
     
       26. A method comprising the steps of:
 establishing communication between a media gateway and a media gateway controller over a first link of a plurality of links; 
 receiving at the media gateway a switchover request from the media gateway controller; 
 monitoring the first link by transmitting an internet control message protocol (ICMP) echo request over the first link and over a second link; 
 waiting for an ICMP reply message within a predetermined period of time on each of the first and second links; 
 when no reply message is received on the first link, transmitting a status message on the second link to indicate a fault on the first link; 
 activating the second link of the plurality of links; and 
 registering the second link for communication of call control signaling information by a higher level process. 
 
     
     
       27. The method of  claim 26  wherein the step of activating the second link of the plurality of links further comprises the steps of:
 transmitting a link activation message for the second link; and 
 receiving a link activation acknowledgement message for the second link. 
 
     
     
       28. The method of  claim 27  wherein the step of registering the second link for communication of call control signaling information by a higher level process further comprises the steps of:
 transmitting a service change message; and 
 receiving a service change reply message. 
 
     
     
       29. The method of  claim 28  wherein the service change message and the service change reply message are H.248 messages transported as user datagram protocol (UDP) packets over internet protocol (IP) over asynchronous transfer mode (ATM) links. 
     
     
       30. The method of  claim 27  wherein the step of transmitting the link activation message for the second link involves the media gateway transmitting the link activation message to the media gateway controller. 
     
     
       31. The method of  claim 30  wherein, for the communication of the call control signaling information, the media gateway controller exerts control over the media gateway. 
     
     
       32. The method of  claim 31  wherein the call control signaling information conforms to Recommendation H.248. 
     
     
       33. The method of  claim 31  wherein, for the communication of the call control signaling information, the media gateway controller further exerts control over a second media gateway coupled to the media gateway controller by a second plurality of links. 
     
     
       34. A method comprising the steps of:
 establishing communication between a media gateway and a media gateway controller over a first link of a plurality of links during an initialization phase; 
 monitoring the plurality of links between a media gateway and a media gateway controller during an operational phase including monitoring the first link by transmitting an internet control message protocol (ICMP) echo request over the first link and over a second link; 
 waiting for an ICMP reply message within a predetermined period of time on each of the first and second links; 
 when no reply message is received on the first link, transmitting a status message on the second link to indicate a fault on the first link; 
 determining a failure affecting the second link of the plurality of the links; and 
 transmitting a link status message regarding the failure affecting the second link from the media gateway to the media gateway controller. 
 
     
     
       35. The method of  claim 34  further comprising:
 sending H.248 signaling messages over the first link during the operational phase. 
 
     
     
       36. The method of  claim 34  wherein, for the communication of call control signaling information during the operational phase, the media gateway controller exerts control over the media gateway. 
     
     
       37. The method of  claim 36  wherein the call control signaling information conforms to Recommendation H.248. 
     
     
       38. The method of  claim 36  wherein, for the communication of the call control signaling information during the operational phase, the media gateway controller further exerts control over a second media gateway coupled to the media gateway controller by a second plurality of links.